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  1.  
  2. import java.util.*;
  3. import java.util.function.*;
  4. import java.util.stream.Collectors;
  5. import java.util.stream.StreamSupport;
  6.  
  7. class Splitting {
  8.     public static void main(String[] args) {
  9.         Map<String, Integer> map = new HashMap<>();
  10.         map.put("a", 1);
  11.         map.put("b", 2);
  12.  
  13.         for(int depth: new int[] { 1, 2, Integer.MAX_VALUE }) {
  14.             System.out.println("With max depth: "+depth);
  15.             Tree<Spliterator<Map.Entry<String, Integer>>> spTree
  16.                 = split(map.entrySet().spliterator(), depth);
  17.             Tree<String> valueTree = spTree.map(sp -> "estimated: "+sp.estimateSize()+" "
  18.                 +StreamSupport.stream(sp, false).collect(Collectors.toList()));
  19.             System.out.println(valueTree);
  20.         }
  21.     }
  22.  
  23.     private static <T> Tree<Spliterator<T>> split(Spliterator<T> sp, int depth) {
  24.         Spliterator<T> prefix = depth-- > 0? sp.trySplit(): null;
  25.         return prefix == null?
  26.             new Tree<>(sp): new Tree<>(null, split(prefix, depth), split(sp, depth));
  27.     }
  28.  
  29.     public static class Tree<T> {
  30.         final T value;
  31.         List<Tree<T>> children;
  32.  
  33.         public Tree(T value) {
  34.             this.value = value;
  35.             children = Collections.emptyList();
  36.         }
  37.         public Tree(T value, Tree<T>... ch) {
  38.             this.value = value;
  39.             children = Arrays.asList(ch);
  40.         }
  41.         public <U> Tree<U> map(Function<? super T, ? extends U> f) {
  42.             Tree<U> t = new Tree<>(value == null? null: f.apply(value));
  43.             if(!children.isEmpty()) {
  44.                 t.children = new ArrayList<>(children.size());
  45.                 for(Tree<T> ch: children) t.children.add(ch.map(f));
  46.             }
  47.             return t;
  48.         }
  49.         public @Override String toString() {
  50.             if(children.isEmpty()) return value == null? "": value.toString();
  51.             final StringBuilder sb = new StringBuilder(100);
  52.             toString(sb, 0, 0);
  53.             return sb.toString();
  54.         }
  55.         public void toString(StringBuilder sb, int preS, int preEnd) {
  56.             final int myHandle = sb.length() - 2;
  57.             sb.append(value == null? "": value).append('\n');
  58.             final int num = children.size() - 1;
  59.             if (num >= 0) {
  60.                 if (num != 0) {
  61.                     for (int ix = 0; ix < num; ix++) {
  62.                         int nPreS = sb.length();
  63.                         sb.append(sb, preS, preEnd);
  64.                         sb.append("\u2502 ");
  65.                         int nPreE = sb.length();
  66.                         children.get(ix).toString(sb, nPreS, nPreE);
  67.                     }
  68.                 }
  69.                 int nPreS = sb.length();
  70.                 sb.append(sb, preS, preEnd);
  71.                 final int lastItemHandle = sb.length();
  72.                 sb.append("  ");
  73.                 int nPreE = sb.length();
  74.                 children.get(num).toString(sb, nPreS, nPreE);
  75.                 sb.setCharAt(lastItemHandle, '\u2514');
  76.             }
  77.             if (myHandle > 0) {
  78.                 sb.setCharAt(myHandle, '\u251c');
  79.                 sb.setCharAt(myHandle + 1, '\u2500');
  80.             }
  81.         }
  82.     }
  83. }
  84.  
Success #stdin #stdout 0.13s 36792KB
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stdin
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Standard input is empty
stdout
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With max depth: 1

├─estimated: 1 [a=1, b=2]
└─estimated: 1 []

With max depth: 2

├─
│ ├─estimated: 0 [a=1, b=2]
│ └─estimated: 0 []
└─
  ├─estimated: 0 []
  └─estimated: 0 []

With max depth: 2147483647

├─
│ ├─
│ │ ├─
│ │ │ ├─estimated: 0 []
│ │ │ └─estimated: 0 [a=1]
│ │ └─
│ │   ├─estimated: 0 [b=2]
│ │   └─estimated: 0 []
│ └─
│   ├─
│   │ ├─estimated: 0 []
│   │ └─estimated: 0 []
│   └─
│     ├─estimated: 0 []
│     └─estimated: 0 []
└─
  ├─
  │ ├─
  │ │ ├─estimated: 0 []
  │ │ └─estimated: 0 []
  │ └─
  │   ├─estimated: 0 []
  │   └─estimated: 0 []
  └─
    ├─
    │ ├─estimated: 0 []
    │ └─estimated: 0 []
    └─
      ├─estimated: 0 []
      └─estimated: 0 []
https://ideone.com/z3f1g0
language:
Java (HotSpot 12)
created:
4 years ago
visibility:
public

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